Electronic sensors generally measure a physical quantity and convert the measured physical quantity into a signal that is provided to an electronic instrument (e.g., integrated chip processor). In recent years, the number of areas using sensors has vastly expanded. For example, sensors can be found in diverse applications such as chemical agent detection units, medical diagnostic equipment, industrial process controls, pollution monitoring, automobiles, etc.
Semiconductor based integrated sensors, such as acceleration or pressure sensors, for example, are available as mass products in automotive and consumer goods electronics. Here, among other things, Micro-Electro-Mechanical Systems (MEMS) are desirable, which integrate a simple threshold switch in an Application Specific Integrated Circuit (ASIC).
When migrating to newer semiconductor process technologies, one challenge is to integrate MEMS such that the complexity of CMOS (Complementary Metal-Oxide-Semiconductor) processes is not unnecessarily increased and existing CMOS integration schemes can be largely retained with minimal development effort. For sub 130 nm process technologies, for example, topology of frontend-of-line structures plays an important role. They should not exceed a total thickness of a few hundred nanometers, so as not to interfere a potential Borophosphosilicate glass (BPSG) polishing act. Furthermore, a reduction to possibly few extra acts and the joint use of existing processes is a prerequisite for successful integration.
Another challenge is the interaction between housing and sensor. In the field of capacitive sensors, the capacitor elements may be subject to considerable stress—depending on the housing type. Often special housings are used which contribute a significant cost component in the overall system.
It is therefore desirable to provide improved microelectromechanical sensor systems taking into account the above mentioned issues.